@article {68, title = {The electromechanics of DNA in a synthetic nanopore}, journal = {Biophys J}, volume = {90}, year = {2006}, month = {2006 Feb 1}, pages = {1098-106}, abstract = {

We have explored the electromechanical properties of DNA on a nanometer-length scale using an electric field to force single molecules through synthetic nanopores in ultrathin silicon nitride membranes. At low electric fields, E < 200 mV/10 nm, we observed that single-stranded DNA can permeate pores with a diameter >/=1.0 nm, whereas double-stranded DNA only permeates pores with a diameter >/=3 nm. For pores <3.0 nm diameter, we find a threshold for permeation of double-stranded DNA that depends on the electric field and pH. For a 2 nm diameter pore, the electric field threshold is approximately 3.1 V/10 nm at pH = 8.5; the threshold decreases as pH becomes more acidic or the diameter increases. Molecular dynamics indicates that the field threshold originates from a stretching transition in DNA that occurs under the force gradient in a nanopore. Lowering pH destabilizes the double helix, facilitating DNA translocation at lower fields.

}, keywords = {Biophysics, Computer Simulation, DNA, Electrochemistry, Electromagnetic Fields, Electrophoresis, Electrophoresis, Agar Gel, Hydrogen-Ion Concentration, Ions, Membrane Potentials, Microscopy, Electron, Transmission, Models, Molecular, Nanostructures, Nanotechnology, Nucleic Acid Conformation, Polymerase Chain Reaction, Porosity, Silicon Compounds, Time Factors}, issn = {0006-3495}, doi = {10.1529/biophysj.105.070672}, author = {Jiunn B Heng and Aleksei Aksimentiev and Ho, C and Patrick Marks and Yelena V Grinkova and S Sligar and Klaus Schulten and Gregory Timp} }